1. Field of the Invention
The present invention relates to a data transfer method used in a display apparatus driving circuit for driving a display apparatus such as a flat display and, more particularly, to an improved data transfer method for a driving integrated circuit, which can reduce the average data transfer amount.
2. Related Background Art
Conventionally, data for one line must be transferred to a driving circuit of a flat display (to be referred to as an FPD hereinafter: Flat Panel Display) since the display operation on the FPD is performed by a line or dot sequential method. More specifically, in a conventional display, all the bits of display data must be transferred in synchronism with the frame frequency. Also, driving data of a driving integrated circuit is updated each time display data is transferred.
FIG. 1 is a physical schematic diagram showing the conventional data transfer method. The system shown in FIG. 1 includes a display apparatus (panel) 1, information line side driving integrated circuits (segment drivers) 2, segment bus boards 5, data buses 7, clock signal lines 8, serial data input signal lines 9, and a controller 10.
FIG. 2 is a schematic diagram of the segment drivers 2 in the conventional data transfer method shown in FIG. 1. The video data buses 7 for supplying video data ID0 to ID7 and the clock signal line 8 for supplying clocks (CLK) are connected in parallel with the segment drivers 2 (2-1, 2-2, 2-3, . . . ), and the serial data input signal (CSDi) line 9 is cascade-connected to these drivers 2. The first segment driver 2-1 receives a serial data input signal CSDi from the controller 10. A serial data output signal a output from the first segment driver 2-1 is connected to the serial data input pin of the second segment driver 2-2, and a serial data output signal b output from the second segment driver 2-2 is connected to the serial data input pin of the third segment driver 2-3.
FIG. 3 is a timing chart in the conventional data transfer method shown in FIG. 1. FIG. 4 is a block diagram showing the arrangement of the driver in the conventional data transfer method shown in FIG. 1.
The conventional data transfer method will be explained below with reference to FIGS. 1 to 4. As shown in FIG. 3, segment image data (video data) for all the drivers are serially transferred in an 8-bit width, and when first data, i.e., D0 to D7, of these image data are supplied, the serial data input signal CSDi simultaneously changes to "1". Then, the first segment driver 2-1 shown in FIG. 2 begins to latch the input image data and simultaneously begins to count the number of clocks. When the segment driver 2-1 has counted 20 clocks CLK, it completes the data input operation, and sets the serial data output signal a to be "1". Similarly, the second and third segment drivers receive image data in the same procedure as described above. With this operation, data D0 to D159 are received as image data of the first segment driver, data D160 to D319 are received as image data of the second segment driver, and data D320 to D479 are received as image data of the third segment driver, thus completing the transfer operation of image data for one horizontal scanning period.
However, in the above-mentioned prior art, since each driving integrated circuit has neither a latch memory nor a multiplexer circuit, sequentially transferred data are latched by a required amount (corresponding to the data holding performance of the integrated circuit), or data corresponding to a sub-scanning width are sequentially transferred using n driving integrated circuits via a shift register to form 1-line data.
Therefore, in the conventional data transfer method, even when a display apparatus with memory characteristics such as a ferroelectric liquid crystal display (to be referred to as an FLCD hereinafter: Ferroelectric Liquid Crystal Display) is to be driven, data for one line are transferred.